Communication devices of various kinds rely on various circuitries to control different aspects of electronic communication between devices. With the rise of wireless communication devices such as mobile phones, smart phones, tablet computers, and other mobile devices that communicate wirelessly, power and battery efficiency become a significant concern. One way to conserve power in a wireless radio is to power down the circuitry of the radio (typically in what is called a low power mode) when the radio is not being used. A problem with this approach is that the radio needs to be a least periodically powered up to detect whether another device is trying to send a communication to the radio. However, this takes a long time to wake up, thereby reducing battery longevity.
One approach to solving this problem is to include a separate lower power radio for detecting the incoming signal. This approach, however, requires more hardware built into the communication device. Another approach is to configure the radio of the communication device to listen for the incoming communication, which approach costs more current and battery life. Moreover, with the increasing abilities of modern communication devices, there is pressure to have the radio wake up process occur in a very fast wake up time with low latency while also conserving battery life.